The general purpose of this work is to study the physical chemistry of solutions of the nucleic acids, particularly DNA. Emphasis will be placed on those aspects of particular importance in laboratory practice. We propose to examine the effects of the charge of the macromolecule on its sedimentation rate and on its diffusion coefficients, both translational and rotational. This will be done using the theory of polyelectrolytes and working out the solutions of the equations on a computer. We will do both experimental and theoretical work on the degradation of long DNA molecules by high flow rates. The experimental work will examine DNA molecules of different molecular weights both in steady and in non-steady flows, both laminar and extensional. The theoretical part will use computer simulation of the motions of a string-of-beads model at high flow rates to examine the distribution of chain configurations and of forces in the chain, and how these change with time. The third part of the work will be an attempt to develop a detailed understanding of the molecular mechanisms of gel electrophoresis, particularly with regard to the dynamic processes involved in the migration of chain molecules through gels. This would be done partly by computer simulation, and partly by measurement of quantities indicative of the mechanisms involved in the migration. Such quantities would be dichroism of DNA in a gel, which would indicate orientation changes during migration, and migrations transverse to the electric field, indicative of the tortuosity of the paths of the molecules through the gel.